1) Field of the Invention
The invention herein relates to an improved structure telescopic-type front fork cushion for bicycles.
2) Background of the Prior Art
To enable additional physical comfort while bicycle riding, shock absorbers are installed on bicycles and today such components are indispensable and, furthermore, crucial to bicycling. The majority of the bicycle shock absorber equipment in use at present are systems installed to curtail shock at the front fork, chainstays, handlebar stem, and seat post. Of these, the said front fork shock absorber systems include linkage and telescopic types, with the telescopic-type accounting for the majority of front fork shock absorbers available on the market and, furthermore, is the type in most widespread usage. The said telescopic-type front fork shock absorber system, as indicated in FIG. 1 and FIG. 2, is comprised of left and right sliders 1, each having a dropout 11 at the outer aspect of the bottom ends into which is installed the center axle of the front wheel A as well as an arch-shaped connective block 12 conjoining the top ends for bracing purposes; installed on the upper ends of the left and right stanchion tubes 2 are the left and right sides of a front fork crown B which enables the structural integrated to the bicycle frame by installing the front fork crown B to the head tube C, with the lower ends of the stanchion tubes 2 then respectively inserted into the left and right sliders 1; upper and lower bushings 4' and 4 are installed on the stanchion tubes 2 and in the sliders 1, respectively, with the said bushings capable of supporting excursive movement, wherein the upper bushings 4' are mounted at the upper ends of the sliders 1 and the lower bushings 4 are mounted in the lower ends of the stanchion tubes 2; left and right cushioning elastic bodies 5 are respectively installed at the bottom section inside the left and right sliders 1, with their upper ends situated against the left and right stanchion tubes 2, thereby enabling the stanchion tubes 2 and sliders 1 to provide a cushioning elastic force to the bicycle frame.
When riding over an irregular road surface, elastic force is transferred to the stanchion tubes 2 and the sliders 1 by the cushioning elastic bodies 5 and then the shock generated by the front wheel A due to the irregular road surface is thereby cushioned and not directly transmitted to bicycle frame C so that the rider experiences more comfortable riding performance. The arrangement of the said telescopic-type front fork shock absorber structure is undeniably capable of bicycle front fork shock absorption and cushioning operation and provides practical value as well as effectiveness and, furthermore, is currently the most wide utilized type. However, following long-term usage, manufacturers have evidently discovered that such simple and economical structures have in actual utilization a few shortcomings that await and, furthermore, require improvement. Since the bicycle front fork is installed in a raked configuration (lower end facing forward and upper end facing rearward), after the front wheel A, bicycle frame C, handlebar, and other components are assembled, this facilitates control by the rider. However, since the upper and lower bushings 4' and 4 that provide for the excursive movement of the stanchion tubes 2 and the sliders 1 are all positioned at the upper extent of the dropouts 11 (specifically referring to the lower bushings 4 installed at the bottom ends of the stanchion tubes 1 that are subject to the travel limits of the cushioning elastic bodies 5 and which are situated at a permanent position at the upper extent of the dropouts 11), therefore, after the center axle of the front wheel A is installed in the said dropouts 11, the said front wheel A on the ground exerts an upward vertical force to the dropouts 11 such that the dropouts 11 become the points of applied force and the upper and lower bushings 4' and 4 become the fulcrum points; thus, when in the course of riding on an irregular road surface an upward force is conveyed from the front wheel A to the dropouts 11 (the points of applied force), the upper and lower bushings 4' and 4 (the two fulcrum points) at their upper extents cause stiction angles to be automatically produced in the stanchion tubes 1 and the sliders 2 due to their raked arrangement; as a result, a greater magnitude of frictional force is generated by the elastic ascending and descending action of the said stanchion tubes 1 and sliders 2, with a corresponding decrease in the smoothness and responsiveness of their kinetic and excursive movement and, at the same time, the cushioning and shock absorption characteristics of the cushioning elastic bodies 5 exhibit the drawbacks of lower sensitivity and positiveness. Specifically, if smoother and more responsive action is to be achieved by the said raked stanchion tubes 2 and sliders 1, the lower bushings 4 (the lower fulcrum points) installed at the bottom ends of the stanchion tubes 2 must be positioned in closer proximity to the dropouts 11 (the points of applied force) and as close as possible for the most optimal results (stiction angles are less likely to be produced the closer the lower bushings 4 are positioned to the points of force); however, this approach significantly affects the travel of the cushioning elastic bodies 5 and greatly detracts the cushioning and shock absorbing performance. Conversely, the farther the position of the lower bushings 4 (the lower fulcrum points) from the dropouts 11 (the points of applied force)--although this advantageously lengthens the travel of the cushioning elastic bodies 5, the greater the degree of the produced friction angles, which precludes the achievement of the claimed objectives of cushioning, shock absorption, and comfortable riding due to the substantial abating of performance by the said shortcomings.
Based on the foregoing section, in the structural arrangement of conventional telescopic-type bicycle front fork shock absorber systems, the upper and lower bushings 4' and 4 that provide for the excursive contact of the stanchion tubes 2 and sliders 1 are situated at the upper extent of the dropouts 11, which in actual application still exhibits utilization shortcomings that await and, furthermore, require improvement.